High frequency circuits, in the microwave range and higher, suitably use transmission lines and transmission line based components such as resonators, matching networks, and power splitters. When designing a transmission line based circuit, important parameters of the transmission line are a characteristic impedance and an electrical length of the transmission line. The electrical length is given by the physical length and the dielectric permittivity of the materials involved, normally the substrate. There is a desire to be able to change the electrical length without having to change the physical length or the substrate material used. A method of attaining this is to connect lumped capacitors periodically to thereby increase the effective permittivity of the transmission line. Connecting lumped capacitors will unfortunately cause the impedance of the transmission line to drop since the characteristic impedance of a transmission line is inversely proportional to the characteristic capacitance of the transmission line, i.e. when the characteristic capacitance increases, then the characteristic impedance decreases. To counteract this, and in cases where a substrate makes it difficult to achieve arbitrary characteristic impedance levels, the width of the signal strip can be decreased to raise the characteristic inductance and thereby raise the characteristic impedance. However, there can be problems with having to decrease the width of the signal strip. It can for example be necessary to decrease the width down to widths that are impossible to manufacture. Narrower signal strips will also have increased losses, which in most cases is very undesirable. In some transmission lines the characteristic impedance can be raised by decreasing the distance between a signal strip and a return conductor/ground plane. This will not change the electrical length of the transmission line. Unfortunately this will also, in most cases, influence the characteristic inductance and other characteristics of the transmission line in a negative manner. There seems to be room for improvement of how to control an electrical length and a characteristic impedance of a transmission line.